Circuit breaker utilizing kinetic energy of trip member to initiate opening of intermediate latch



Malh 16, 1965 s. A. BOTTONARI ETAL 3,174,010

CIRCUIT BREAKER uTIETzING KINETIC ENERGY oF TRI|J MEMEER To INITTATEOPENING 0E INTERMEDIATE LATCH Filed June 27, 1961 WITNESSES: INVENTORSSamuel A. Bottonori ond @www Robert E. Wobrok.

l l )naam 5, MA k, F. 2

'g' ATTORNEY United States Patent O CIRCUH BREAKER UTILIZING KINETICENERGY F TREE MEMBER T INHIATE OPENING 0F TERMEDIATE LATCH Samuel A.hottonari, Wilkinshurg, and Robert E. Wobralk, North HuntingdonTownship, Westmoreland County, Pa., assignors to Westinghouse ElectricCorporation, Pittsburgh, Pa., a corporation of Pennsyivania Filed `Ilune27, 1961, Ser. No. 119,851 d Claims. (Cl. G-1116) This invention'relates to circuit breakers and more particularly to operatingmechanisms for circuit breakers.

In the patent to J. D. Findley, Jr., et al., Patent No. 2,515,994,issued July 18, 1950 Vand -assigned to the assignee of the instantapplication, there is disclosed ya circuit breaker comprising `a latchedoperating mechanism that is releasable to effect opening of the breaker.The operating mechanism comprises a main latch that is held in latchingposition by -an intermediate latch that is pivotally mountedintermediate its ends and has a roller on one end thereof that engagesthe main latch. A trip member engages a roller on the other end of theintermediate latch to hold the intermediate latch in latching position.Spring means are provided to bias the operating mechanism toward theopen position. In order to eiiect an opening operation, the trip memberis moved either manually or by means of an automatically operatedelectromagnet to release the intermediate latch whereupon the force ofthe opening spring means moves the main latch to force the intermediatelatch to move to the unlatched position to completely release the mainlatch whereupon tl e operating mechanism is rapidly moved to open thebreaker.

lf the intermediate latch in the above described mechanism becomesjammed in the latching position, the breaker will not automatically tripupon the occurrence ot an overload current and serious damage can occurin the circuit that is to be protected by the breaker.

Accordingly, an object of `this invention is to provide a circuitbreaker of the above-mentioned type with improved means for initiatingopening movement of the intermediate latch in order to effect a trippingoperation.

Another object of the invention is to utilize kinetic energy of the tripmember to initiate opening movement of the intermediate latch of theoperatingr mechanism of the circuit breaker.

A more general object of this invention is to provide a circuit breakerwith improved means for effecting opening movement of the operatingmechanism of the breaker.

The novel features that are considered characteristic of the inventionare set forth in particular in the appended claims. The inventionitself, yboth as to structure and oper-ation, together with additionalobjects and advantages thereof, will be best understood from thefollowing detailed description when read in conjunction with theaccompanying drawings, in which:

FIGURE l is a side elevational View, partly in section, of a circuitbreaker embodying the principles of this invention; and

PEG. 2 is an elevational view, partly in section and enlarged relativeto the dimensions shown in FIG. 1, of part of the mechanism of thecircuit breaker seen in FIG. 1.

The structure of the circuit breaker shown in FIG. l is specificallydescribed in the above mentioned patent to l. D. Findley, r., et al.,for which reason only a brief description of the breaker is givenherein.

Referring to the drawings, and particularly to FIG. 1 thereof, a circuitbreaker 3 of the roll-out type is mounted on a truck comprising a pairof side plates 11 (only one being shown) which are rigidly joined bycross members hee 13, 15, 17 and 19 to form a rigid frame for supportingthe parts of the breaker. The truck is mounted on wheels 20 tofacilitate rolling the circuit breaker into and out of a cubicle (notshown) in order to connect and disconnect the breaker in an electricalcircuit.

The circuit breaker 3 is of the multi-pole type (only one pole beingshown) and it comprises 4a plurality of sets of separable contact means21, .a common operating mechanism 23, a trip device 25 and solenoidclosing means 27.

The contact means 21 comprises stationary contact blocks 29 and 31mounted on upper and lower terminal members 33 and 35 respectively whichterminal members are rigidly supported on a back plate 37. The backplate 37 is supported by `angular brackets 39 (only one being shown)that are rigidly secured to the side plates 11 of the trame. A switcharm 41 pivotally mounted on a stud 43 on the llower terminal member 35,carries a bridging contact member 45 for cooperating with the stationarycontacts 29 and 31 to eiect opening and closing of the circuit that iscontrolled by the breaker. The switch arm l1 carries a movable arcingcontact 47 which cooperates with a stationary arcing Contact 49 that ismounted on the upper terminal member 33 for drawing an arc upon openingmovement of the switch arm 41.

There lis a switch arm 41 for each pole of the circuit breaker 3 andeach of the switch arms 41 is operatively connected by means of aninsulating operating rod 51 to the common operating mechanism 23 forsimultaneous operation. The upper ends of the operating rods 51 arepivotally connected by means of pivot pins 53 to the correspondingswitch arms 41 land the lower ends of the operating rods 51 Iareconnected by suitable means to an angular cross bar 59 that is common toall of the poles of the breaker. The cross bar 59 is pivotally connectedby means of pivot pins 55 (only one being shown) to an operating lever61. The operating lever 61 is pivotally supported on a shait o7 that ismounted in the side members of a generally U-shaped frame 69 that issupported on the cross members 13, 15 and 17. The trame 69 is shownpartly broken away to more clearly illustrate the operating mechanism23.

In addition to the operating lever 61, the operating mechanism 2,3comprises `a closing lever that is also mounted on the shaft 67 whichclosing lever is connected by means of a link 81 to a movable armature85 of the solenoid closing means 27. The operating lever 61 and theclosing lever 75 are connected by means of an underset thrusttransmitting toggle comprising toggle links 87 and 89 that are pivotallyconnected together by means of a knee pivot pin 91. The toggle link 87is pivotally connected to the operating lever o1 by means of a pivot pin92;. The toggle `link 89 is pivotally connected to the closing lever 75by means of a pivot pin 76. The lever 75 is also connected to the lever81 by means of the pivot pin 76.

rlhe closing lever 75 is held in the closed position by means `of `aspring biased latch 95 that is pivoted on a pin 97 that is supported inthe side members of the frame 6%. The latch 95 is biased, by means of aspring 96, into engagement with a roller 1611 that is mounted on thepivot pin 76 which engagement normally holds the lever 75 in the closedposition shown.

The toggle 87, 89, is normally held in `a slightly underset position bymeans of a main latch 1613 that is rotatably mounted on the shaft 67 andis connected by meanscf a link to the knee 91 or the toggle. The link105 is connected to the latch 103 by means of a pivot pin 1117.

The main latch 163 is normally releasably restrained in lratchingposition by means ot the latching and tripping mechanism 25. Thelatching and tripping mechanism 25 airs-,oto

comprises fan intermediate latch or latch structure 169 that ispivotally supported intermediate its ends on a pin 111 that is supportedon a bracket 112 (FIG. 1). A roller 113 (FIG. 2) is rotatably supportedon a pin 115 disposed at one end of the intermediate latch 109 whichroiler engages the main latch 103. The intermediate latch 109 comprisestwo twin members 114 connected by a cross member 116. A roller 117 isrotatably supported on a pin 119 `at the other end of the intermediatelatch 1119. The roller 117 normally engages a depressed surface 121 of atrip member 123. The trip member 123 is pivotally supported on a pin 12dthat is supported on the bracket 112 (FIG. 1). The intermediate latch109 is biased toward the latching position by means of a torsion spring125. The trip member 123 is biased toward latching position by means ofa torsion spring 126.

The trip member 123 is adapted to be operated either manually or.automatically in a clockwise direction to an unlatching position, toeffect release of the intenmediate latch 109 to thereby effect releaseof the operating mechanism 23 and opening of all of the pole units ofthe circuit breaker, by means of a tripping electromagnet indicatedgenerally at 137 (FIG. l).

The tripping electromagnet 137 comprises la support member 139 that issecured to a plate 141 that is rigidly mounted on the U-shaped frame 69.In `addition to the support bracket 139, the tripping electromagnet 137includes an energizing coil 143, a movable armature (not shown) .and atrip rod 145 that is attached to the movable armature.

The closing solenoid 27 (FlG. 1) in Aaddition. to the movable armature65, comprises a lined core member V147 and an energizing coil 1419. Theclosing solenoid 27 is supported between the side members of the frame69 and an end plate 151, which end plate is suitably secured to theframe 69, by means of bolts 153 and spacers 155.

The circuit breaker is shown in F1G. 1 in the closed and latchedposition. In the closed and latched position, the operating lever 61 isbiased in a clockwise or opening direction by means of an opening spring159 that is disposed in a cylinder 161 that is rigidly mounted on theframe 69. A piston 163 disposed for reciprocal movement in the cylinder161 is connected by means of a link 165 to an arm portion 166 of theoperating lever 61. The cylinder 161 and piston 163 also serve as .adashpot to absorb the shock of the opening operation of the operatingmechanism. The spring 159 acting through the piston 163 `and the link165 biases the operating lever 61 in a clockwise direction. The biasing`force of the spring 159 is transmitted by means of the underset toggle87, 39 to the closing lever 75 which is normally restrained in theposition shown in FIG. l by the latch 95. The force of the spring 159,therefore, tends to cause the toggle 87, 89 to collapse which movementis prevented by the link 105 and the latching mechanism. A component ofthe force tending to collapse the toggle 87, 89 is applied through thelink 105 to the latch member 1113 tending to rotate this member in acounterclockwise direction about the pivot 67. The -latch member 103 isrestrained from this tripping rotation by the slip-oit or roll-olf typeengagement with the roller 113 of the intermediate latch 169, whichintermediate latch is restrained from counterclockwise tripping movementby engagement of the lroller 117 thereon in the depressed surface 121 ofthe tripping member 123.

Upon the occurrence of an abnormal current condition, such for exampleas an excessive overload current in the circuit controlled by thecircuit breaker, the tripping electromagnet 137 (FIG. 1) is energized bywell known means such, for example, as a fault relay. When the trippingelectromagnet 137 is energized, the movable armature (not shown) thruststhe trip rod 145 upward to engage the trip member 123 moving the tripmember in a clockwise or tripping direction. Clockwise movement of thetrip member 123 disengages the roller 117 (FIG. 2) from the depressedsurface 121 in the trip member 123 to unlatch the intermediate latch orlatch structure 109. As soon as the intermediate latch 1119 isunlatched, because of the slip-off or roll-oit type engagement of themain latch 163 with the roller 113 on the intermediate `latch 1119, theforce tending to collapse the toggle 87, 89, a component of which isapplied to the latch member 103, forces the intermediate latch 1119 tomove countercl-ockwise or in unlatching direction out of the path of themain latch 103, whereupon the main latch 163 is `free to rotatecounterclockwise in a tripping direction and it no longer maintains thetoggle 87, S9 in its underset position. Upon release of the latch member103, the toggle 37, S9, therefore, immediately collapses under theinfluence of the opening spring 159 the force `of which spring operatesimmediately to rotate the operating lever 61 in a clockwise direction tomove the common cross bar 59 :and `all of the movable contact farms 51to the open position opening all of the circuit breaker con-tact means21.

The toggle 87, S9 is reset to its underset position and the main latchmember 1113 is reset and relatched during the opening operation. Theresetting of the toggle S7, 89 and the relatching of the latch member163 is effected by means of a pair of springs 169 (only one being Shown)each of which is secured at one end to` a bracket 171 that is secured tothe armature S5 and at the other end to a portion of the closing lever75. During the collapse of the toggle S7, 89, a roller 175 that ismounted on a pin 177 that is secured to the toggle S9, engages aprojection 179 on the latch 95 and moves the latch 95 downward torelease the closing lever 75. The closing lever is connected at 76 tothe link 81 forming a toggle therewith. The springs 169 are tensionedbetween the lever 75 and the link 51 acting on these members to decreasethe obtuse angle between them. This movement can be effected only bymovement of the link S1 to the left which latter movement is normallyprevented by the latch 95. Upon release of the latch 95, there is nolonger any restriction to this movement of the link S1 and the springs169 act to move the link 81 and armature 85 to the left rotating thelever 75 clockwise until it strikes a stop member (not shown). Clockwiserotation of the lever '75 straightens the toggle 87, 89. Straighteningof the toggle 67, 89 thrusts the link 195 to the left thereby rotatingthe main latch 163 clockwise to its latching position, at which time theintermediate latch 169 is moved by the spring 126 (FIG. 2) to a positionin which the roller 113 re-engages with the main latch 103.

After the mechanism is reset and relatched following an automaticopening operation, the contacts are closed by energization of theclosing solenoid 27. The solenoid 27 may be energized from any suitablesource either automatically or by means of a manually operated switchmeans. When energized, the solenoid 27 attracts its armature and,through the link 81, rotates the closing lever 75 in a counterclockwisedirection about the shaft 67. At this time, the main latch member 163 isrestrained in latching position and the toggle 87, 89 is held by thelink in thrust transmitting position. The counterclockwise or closingmovement of the closing lever 75 is, therefore, transmitted through thetoggle 57, 89 to the operating lever 61 to rotate the operating lever 61counterclockwise to its closed position to thereby move the operatingrods 51 and the switch arms 11 for all of the poles of the breaker tothe closed position shown in FIG. l. As the operating mechanism arrivesat its closed position, the latch 95, biased by the spring 96,re-engages the latch roller 101 to restrain the pin 76 and therefore theoperating mechanism 23 and the contact means 21 in the closed position.The final closing movement of the operating mechanism is retarded bymeans of the opening spring 159 which spring is charged during theclosing operation.

The contact means 21 of the circuit breaker are tripfree of the closingmeans. That is, if, when the circuit breaker is operated to the closedposition, the overload current condition has been cleared, the breakerwill remain in the closed position. However, should the overload currentstill persist, the tripping electromagnet 137 will be energized uponclosure of the contacts to operate the tripping mechanism 2S in thepreviously described manner to effect immediate release of the latchmember 193 and collapse of the toggle d'7, 89. This movement permits thecircuit breaker mechanism including the switch arms d1 for all of thepoles of the breaker to go to the open position under the bias of theopening spring 159, even though the closing solenoid 2.7 remainsenergized and/ or irrespective of the position of the closing lever '75.

The engagement of the roller 113 of the intermediate latch 109 with themain latch 1&3 is a slip-ott or roll-olf type engagement so that upontripping movement of the trip member 123, the force of the openingspring 159 exerted through the operating mechanism, rotates the member103 to move the intermediate latch 1d@ in unlatching direction toeil'ect an opening operation. The force exerted by the spring 1d@ isreduced through the operating mechanism 23 so that the intermediatelatch 1% is moderately loaded. This meets the general requirements ofhaving a system that releases a mechanism of considerable force whichsystem does not require a high etlort source to effect a trippingoperation. Thus, for example, the force exerted by the operating springS may be a force of 400 pounds when the circuit breaker is in the closedposition, which force is reduced in components through the operatingmechanism 2? to la force of about 6 pounds or less tending to rotate theintermediate latch 1&9 in unlatching direction. lt can be understoodthat if a foreign impediment such as a piece of contact that might spawloff of the contact structure becomes lodged between the roller 113 andthe main latch 1%, this impediment could restrain tripping movement ofthe intermediate latch 1G@ to thereby prevent tripping of the circuitbreaker even though the forces exerted by the operating spring 159 areconsiderable. lt the circuit breaker 3 fails to trip upon the occurrenceof an excessive overload condition even though the electromagnet 137 isenergized to effect tripping movement of the trip member 123, thecircuit breaker will remain closed an extensive damage will result inthe circuit that is to be protected by the circuit breaker.

improved means are provided by this invention for initiating openingmovement of the intermediate latch or latch structure il@ to therebyavoid failure of opening movement of the intermediate latch 169.Referring to HG. 2, a projection 133 is provided on the intermediatelatch 109 which projection is disposed in the path of movement of thetrip member 123. Thus, the projection 183 receives a iinal impact blowfrom the back surface of the trip member 123, as shown in dot-dash linesin FiG. 2, upon tripping movement of the trip member 123 to therebyinitiate movement of the intermediate latch 169 in a counterclockwise oropening direction. Once this opening movement of the intermediate latch1%9 is started, the increasing component of force exerted through themain latch 103 will rapidly complete the opening operation in the samemanner hereinbefore described.

The projection 183 can be disposed or positioned to receive a blow fromthe trip member 123 upon each automatic tripping or manual openingoperation; or it may be positioned such that it will receive a bleu fromthe trip member 123 only upon failure of the forces exerted through themain latch 1.@3 to initiate movement of the intermediate latch 169. lnthe latter case, during a normal opening or tripping operation, theintermediate latch 109 will start to move immediately upon 'trippingmovement of the trip member 123 so that the projection 1?3 on theintermediate latch will move ahead of the trip member 123 during thetripping operation. If the intermediate latch 109 fails to moveimmediately upon tripping movement of the trip member 123, the member123 will engage the projection 183 imparting a blow against thisprojection to initiate opening movement of the intermediate latch 1w.

As was hereinbefore explained, due to the resolution of the openingforce components through the system of levers and latches, a force of,for example, 400 pounds exerted by the spring means 159 is reduced to aload of less 'than 6 pounds tending to rotate the intermediate latch1%9. The mechanism can be so constructed that the force oi the latchmember 163 will pass through the center of the pivot 111 of theintermediate latch 109 so that the component of force tending to rotatethe latch 169 Will be zero. in such a structure the trip member 123 willengage the projection 183 on each opening or tripping operation. Theslightest change in position of the intermediate latch 109, occasionedby the blow imparted by 'the trip member 123, will cause an increasingmoment of force exerted by the main latch 103 against the roller 113moving the intermediate latch clear of the main latch 193. ln thisembodiment, the force required to effect opening or tripping movement ofthe trip member 123 is reduced to a minimum.

From the foregoing description, it is apparent that there is provided animproved circuit breaker comprising improved means for effecting openingor tripping movement of the mechanism to eect opening of the circuitbreaker.

While the invention has been disclosed in accordance with the provisionsof the patent statutes, it is to be understood that various changes inthe structural details thereof may be made Without departing from someof the essential features of the invention. lt is desired, therefore,that the language of the appended claims be given the broadestreasonable interpretation permissible in the light of the prior art.

We claim as our invention:

l. A circuit breaker comprising, in combination, a stationary contact, amovable contact, a movable contact arm carrying said movable contact andmovable to open and close said contacts, an operating mechanismcomprising a iirst latch member releasable to effect opening movement ofsaid movable contact arm, a second latch member being releasable andwhen released normally moving to eiect release of said first latchmember, a trip member in a first and latching position engaging saidsecond latch member to latch said second latch member and being movableto a tripping position to release said second latch member, and upontripping movement of said trip member, means on said trip memberoperating to strike said second latch member to initiate releasingmovement of said second latch member if said second latch member hasfailed to normally move when it is released.

2. A circuit breaker comprising, in combination, a stationary Contact, amovable contact, a movable contact arm carrying said movable contact andmovable to open and close said contacts, an operating mechanismcomprising a first latch member releasable to eiect opening movement ofsaid movable contact arm, a second latch member being releasable andwhen released normally moving to effect release of said iirst latchmember, a trip member movable to a tripping position to release saidsecond latch member, means biasing said operating mechanism toward theopen position, and upon tripping movement of said trip member meansoperable to initiate releasing movement of said second latch member byimparting a blow against said second latch member only if said secondlatch member fails to normally move when it is released.

3. A circuit breaker comprising, in combination, a stationary contact, amovable contact, a movable contact arm carrying said movable contact andmovable to open and close said contacts, a toggle collapsible to effectopening movement of said movable contact arm, means biasing said toggletoward the collapsed position, a first latch member releasable to permitcollapse of said toggle, a second latch member releasable to normallymove to eiect release of said first latch member, a trip member movableto a tripping position to release said second latch member, and meansoperable upon tripping movement of said trip member to strike saidsecond latch member to initiate releasing movement of said second latchmember only if said second latch member does not normally move when itis released.

4. A circuit breaker comprising, in combination, a stationary contact, amovable contact, a movable Contact arm carrying said movable contact andmovable to open and close said contacts, a rst latch member releasableto move to an open position to eitect opening movement of said movablecontact arrn, means biasing said first latch member toward the openposition, a latch structure pivotally mounted intermediate its ends, oneend ot said latch structure engaging said rst latch member to preventrelease of said rst latch member, said latch structure being releasableto normally move to release said lirst latch member, a trip member, saidtrip member engaging the other end of said latch structure 'to preventreleasing movement of said latch structure, said trip member beingmovable to a tripped position to release said latch structure, and upontripping movement of said trip member means movable with said tripmember and. operable only when said latch structure does not normallymove when said latch structure is released to strike a part of saidlatch Structure to initiate releasing movement of said latch structure.

References (Cited by the Examiner UNTED STATES PATENTS 2,125,139 7/38Schofield 20G- 106 2,515,994 7/50 Findley et al. ZOO-89 2,601,417 6/52Scott 200-106 2,695,345 11/54 Scott ZOO- 89 2,712,577 7/55 Stene ZOO-1062,937,258 5/66 Starr 20S- 619 FOREIGN PATENTS 142,860 i0/ 30Switzerland. 415,393 9/34 Great Britain.

BERNARD A. GLHEANY, Primary Examiner.

MAX L. LEVY, Examinez'.

1. A CIRCUIT BREAKER COMPRISING, IN COMBINATION, A STATIONARY CONTACT, AMOVABLE CONTACT, A MOVABLE CONTACT ARM CARRYING SAID MOVABLE CONTACT ANDMOVABLE TO OPEN AND CLOSE SAID CONTACTS, AN OPERATING MECHANISMCOMPRISING A FIRST LATCH MEMBER RELEASABLE TO EFFECT OPENING MOVEMENT OFSAID MOVABLE CONTACT ARM, A SECOND LATCH MEMBER BEING RELEASABLE ANDWHEN RELEASED NORMALLY MOVING TO EFFECT RELEASE OF SAID FIRST LATCHMEMBER, A TRIP MEMBER IN A FIRST AND LATCHING POSITION ENGAGING SAIDSECOND LATCH MEMBER TO LATCH SAID SECOND LATCH MEMBER AND BEING MOVABLETO A TRIPPING POSITION TO RELEASE SAID SECOND LATCH MEMBER, AND UPONTRIPPING MOVEMENT OF SAID TRIP MEMBER, MEANS ON SAID TRIP MEMBEROPERATING TO STRIKE SAID SECOND LATCH MEMBER TO INITIATE RELEASINGMOVEMENT OF SAID SECOND LATCH MEMBER IF SAID SECOND LATCH MEMBER HASFAILED TO NORMALLY MOVE WHEN IT IS RELEASED.